1. Field of the Invention
This invention relates to new and improved ultrasonic method and apparatus for non-invasive biophysical diagnosis.
2. Description of the Prior Art.
Although prior art acoustical interrogation methods and apparatus in the nature of those disclosed, for example, in our U.S. Pat. No. 3,830,223 of Aug. 20, 1974 entitled "Methodology And Apparatus For Non-Invasive Biophysical Diagnosis," are known which effect coherent detection, i.e. detection of both amplitude and phase in the reflected acoustical energy pulses, and which operate through deconvolution of the echo signal train to provide a particularly precise impedance profile of the acoustically interrogated material, it may be understood that such prior art methods and apparatus operate to mathematically deconvolve the echo signal train in the time domain. This time domain deconvolution can, under conditions of certain echo signal train characteristics, result in mathematical instabilities in the deconvolution equation which are difficult to discover and overcome, and which can in turn result in loss of some of the information bearing attributes of the echo signal train with attendant degradation of the provided impedance profile resolution. In addition, essential echo signal processing techniques such as amplification and filtering are, under certain conditions, rendered difficult by time domain deconvolution. Too, it may be understood that the essential source function characteristics in the nature of bandwidth, and the overall characteristics of the acoustical focusing apparatus and methods of the prior art are, in many instances, not determined and/or operable with sufficient preciseness to afford high degrees of resolution and are not, in any event, suitably interrelated with the echo signal train deconvolution equation to maximize the mathematical stability of the latter.